Summary
An information disclosure vulnerability in OpenClaw's tools.exec.safeBins approval flow allowed a file-existence oracle.
When safe-bin validation examined candidate file paths, command allow/deny behavior could differ based on whether a path already existed on the host filesystem. An attacker could probe for file presence by comparing outcomes for existing vs non-existing filenames.
Affected Packages / Versions
- Package:
openclaw(npm) - Affected versions:
<= 2026.2.17 - Latest published vulnerable version at triage time:
2026.2.17 - Planned patched version:
2026.2.18
Fix Commit(s)
bafdbb6f112409a65decd3d4e7350fbd637c7754
Found using MCPwner
Thanks @nedlir for reporting.
Impact
Attackers with access to this execution surface could infer whether specific files exist (for example secrets/config files), enabling filesystem enumeration and improving follow-on attack planning.
CVE-2026-4040 has a CVSS score of 4.3 (Medium). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2026.2.19); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
The safe-bin policy was changed to deterministic argv-only validation without host file-existence checks. File-oriented flags are blocked for safe-bin mode (for example sort -o, jq -f, grep -f), and trusted-path checks remain enforced.
Frequently Asked Questions
- What is CVE-2026-4040? CVE-2026-4040 is a medium-severity security vulnerability in openclaw (npm), affecting versions <= 2026.2.17. It is fixed in 2026.2.19.
- How severe is CVE-2026-4040? CVE-2026-4040 has a CVSS score of 4.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of openclaw are affected by CVE-2026-4040? openclaw (npm) versions <= 2026.2.17 is affected.
- Is there a fix for CVE-2026-4040? Yes. CVE-2026-4040 is fixed in 2026.2.19. Upgrade to this version or later.
- Is CVE-2026-4040 exploitable, and should I be worried? Whether CVE-2026-4040 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-4040 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-4040? Upgrade
openclawto 2026.2.19 or later.